Downloadable Content

Descriptions

A rapid virus detection method was developed for Infectious Hemotopoietic Necrosis Virus (IHNV). The virus detection method could be applied to Infectious Pancreatic Necrosis Virus (IPNV) under certain conditions. It was possible to detect IHNV to a lower limit of 1.7 X 10⁴ Tissue Culture Infectious Dose for 50% (TCID₅₀) units per millileter under experimental conditions. IPNV, Buhl strain, was detected at 3.55 X 10⁶ TCID₅₀ units per ml. The method for rapid diagnosis involves electron microscopic examination of a sample obtained by sedimenting virus from a known volume of sample onto collodion coated grids. This virus detection method can be used to determine the IHNV concentration in hatchery effluent water. The method can also be used to detect virus in infected sex products of adult fish and on infected eggs. In water samples that have been clarified of debris and cellular components, IPNV can be detected. In some cases, the virus sample can be concentrated from water and then sedimented onto grids for electron micro scopy. ii Particle to infectious virus ratios were determined for three strains of IPNV and IHNV. IPNV ratios were 2.5:1 for Buhl strain; 100:1 for VR 299 strain; and 9:1 for Cascade Lockes strain. These ratios were similar to those reported in the literature for IPNV (Chang, et al., 1978). IHNV had particle to infectivity ratios of 500:1 to 1,400:1. Calculation methods of Chang et al. (1978) and Sharp (1965) were used to enumerate the virus from electron micrographs for IHNV.